The present invention relates to fiber optic connectors for use in optical fiber signal transmission systems, and to methods for assembling such fiber optic connectors.
Fiber optic cables are used in the telecommunications industry to transmit light signals in high speed data and communication systems. A standard fiber optic cable includes an inner light transmitting fiber surrounded by a coating layer of a polymeric material such as nylon. The coating layer is surrounded by a reinforcing or strength layer (e.g., Kevlar) that is covered by an outer casing or jacket made of a polymeric material such as polyvinyl chloride (PVC).
Fiber optic connectors are frequently used to non-permanently connect and disconnect optical elements in a fiber optic transmission system. There are many different fiber optic connector types. The most prevalent optic connectors are FC and SC connectors. Other common types of connectors include ST and D4-type connectors.
A typical fiber optic connector includes a housing having a front end positioned opposite from a rear end. The front end of the housing is commonly configured to be inserted within an adapter. A fiber optic cable is usually inserted into the connector through a passage (commonly referred to as a capillary) defined by the rear end of the housing. The connector typically includes a ferrule that is mounted adjacent the front end of the housing. The ferrule is axially moveable relative to the housing, and is spring biased toward the front of the connector. The fiber optic cable has an end that is stripped. The stripped end includes a bare fiber that extends through the ferrule, and a buffered portion that extends through the remainder of the connector. Adhesive (e.g., epoxy) is used to secure the fiber within the ferrule. The adhesive is often applied by a needle inserted through the passage defined by the rear end of the housing. A reinforcement layer of the fiber optic cable is frequently crimped to the rear end of the housing.
When a connector such as the connector described above is used to provide a fiber optic connection, the ferrule is typically forced to slide rearwardly within the housing. In concert with the movement of the ferrule, the buffered portion of the cable also slides relative to the housing. It is important for the buffered portion to be capable of sliding relative to the housing because, absent such capability, the fiber may break when the ferrule is moved. Misapplied adhesive within the connector housing has been known to cause the buffered portion to xe2x80x9clock-upxe2x80x9d within the housing (i.e., the buffered portion becomes adhesively bonded to the housing) such that the buffered portion is prevented from sliding relative to the housing. Thus, in assembling a fiber optic connector, it is desirable to have safeguards for ensuring that the buffered portion is free to slide relative to the housing. Safeguards are particularly important when assembling connectors for small diameter fiber optic cables because such connectors have small inner diameters creating a situation where adhesive can inadvertently be misapplied to the small inner diameters. This is problematic because when cables are subsequently inserted in the connectors, the misapplied adhesive can cause the buffered portions of the cables to xe2x80x9clock up.xe2x80x9d It is also desirable for fiber optic connectors to be capable of receiving fiber optic cables having different diameters.
One aspect of the present invention relates to a fiber optic device including a fiber optic connector and fiber optic cable secured to the connector. The fiber optic connector includes a first housing piece that extends along a longitudinal axis. The first housing piece includes a front end positioned opposite from a rear end. The first housing piece also defines an inner chamber. A hub is positioned within the inner chamber of the first housing piece. The hub includes a passage that extends along the longitudinal axis of the first housing piece. The hub is slidable along the longitudinal axis relative to the first housing piece. A ferrule is connected to the hub. The ferrule extends along the longitudinal axis from the hub toward the front end of the first housing piece. The ferrule defines a passage that extends in general axial alignment with the passage of the hub. A second housing piece is positioned at the rear end of the first housing piece. The second housing piece defines a passage that is in general alignment with the passage of the hub. A spring is captured between the hub and the second housing piece for biasing the hub toward the front end of the first housing piece. The connector further includes a third housing piece that is non-unitarily connected to the second housing piece. The third housing piece defines a passage that is in general axial alignment with the passage of the second housing piece. The third housing piece includes an outer crimp region against which a portion of the fiber optic cable is crimped. The fiber optic cable includes a fiber that extends through: (1) the passage of the ferrule; (2) the passage of the hub; (3) the passage of the second housing piece; and (4) the passage of the third housing piece.
Another aspect of the present invention relates to a method for assembling a fiber optic device. The method includes providing a connector including a housing having a first end positioned opposite from a second end. The connector also includes a ferrule that is spring biased toward the first end of the housing. The ferrule defines a longitudinal ferrule passage. The second end of the housing defines an access opening. Adhesive is provided to the ferrule passage by inserting an adhesive delivering tool through the access opening. After the adhesive has been provided to the passage of the ferrule, an extension piece is connected to the second end of the housing. Also after the adhesive has been provided, a fiber of a fiber optic cable is inserted within the ferrule passage. The method further includes inserting at least a portion of the fiber optic cable through the extension passage and the access opening, and securing at least a portion of the fiber optic cable to an exterior of the extension piece.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of the invention as claimed.